                                              (set-of [g m] [[g pos _] counterexamples,
                                                             m pos])))))
                ;;
-               true                    ; add implication
+               true                     ; add implication
                (let [new-implications (conj implications new-impl)]
                  (recur new-implications
                         (next-closed-set (attributes possible-ctx)

                                      :abort))]

              (cond
               (= counterexamples :abort)
               (recur implications nil possible-ctx certain-ctx) ; abort exploration
               ;;
               counterexamples         ; add counterexample
               (let [new-objs (map first counterexamples)]
                 ;; check that new names are not there already
                 (when (exists [g new-objs] (contains? (objects possible-ctx) g))

                                     [possible-context certain-context]),
        background-knowledge       (or background-knowledge #{}),
        handler                    (or handler default-handler-for-incomplete-counterexamples)]
    ;; check arguments
    (assert (set? background-knowledge))
    (assert (= (attributes certain-ctx)
               (attributes possible-ctx))
